This invention relates generally to construction lifts and more particularly to a self-climbing high-rise lift for use on the outside of a building under construction in the preferred embodiment.
In the erection of high-rise type buildings consisting of a large plurality of floors, it is common to erect on the outside of the steel construction a plurality of man-lifts which are utilized for the stocking of the respective floors with the material needed to complete those floors. There is also usually constructed prior to the erection of the steel in the building, a crane known as a tower crane which is designed to be used to lift the steel to be erected into its skeleton shape. The tower crane is also utilized for the lifting of outside facing panels on the building if such panels are incorporated into the design.
Other forms of lifting devices common in building construction would consist of guy derricks which go up with the building approximately every three floors and can be used also to put up the steel in the building. A problem encountered with guy derricks is that they cannot be used to erect the facing panels of the building. The previously described man-lift, fastened on the side of the building is generally not capable of lifting the facing panels without special handling. In order to use a man-lift for facing panels, the panels must first be positioned upright in the man-lift and then removed from the top of the man-lift at the appropriate floor. This procedure becomes expensive since it is time-consuming. It is also known in the construction industry to lift the facing panels with a stiff-legged crane or a Chicago boom which has been mounted on the outside of the building. The use of each type of separate lift becomes expensive also thereby raising the overall cost of building erection.
Inasmuch as the cost of renting a tower crane can be approximately 25 thousand dollars per month which would include the rental of the crane and the use of two operators and insurance on the crane, it can be seen how the use of the tower crane for purposes of lifting facing panels and lifting other heavy objects up to the building erection site becomes very costly.
Other problems encountered with the use of a tower crane are inherent in the crane's structure. For example, a tower crane takes 6 to 12 hours to raise three floors with its associated counterweights and all of the equipment needed for the crane. Since the tower crane is generally tied to the steel structure for a distance of at least five floors it can be seen that there is a massive amount of weight in the range of two-hundred seventy thousand pounds which can be eliminated during construction if the tower crane itself can be eliminated.